Shoreline erosion is a serious problem along the shores of large bodies of water due to the wave action typically taking place on large bodies of water. Problems associated with shoreline erosion can be even more serious if recreational, residential, and commercial areas along the shoreline are developed right up to the shoreline. Oftentimes, there are structural improvements present at or near the shoreline, such as private beach homes, hotels, bridges, retaining structures, and the like, wherein shoreline erosion progressively undermines the foundations of these structures, threatening the physical integrity of the structures over time. Furthermore, shoreline regions also depend on beach tourism as their main industry; and thus, beach erosion can cause these regions significant economic harm by removing the main tourist attraction.
Shorelines along bodies of water, such as rivers, large lakes, and oceans, can erode from natural erosive processes that removes material from the shoreline, often referred to as “scour.” Scour occurs when moving water suspends sand, sediment, or other seafloor material at one location in the flowing water and then redeposits the material at some other location. Many factors specific to the particular shoreline and water velocities can enhance this erosion phenomenon.
Another significant factor enhancing the erosion process is the velocity of the water passing across the shoreline. In order to initiate scour, the water must move at a velocity greater than a critical “suspension velocity” to suspend the sediment of the shoreline in the moving water. The suspension velocity required to initiate scour is dependent upon many location specific factors, such as the geometric shape of the shoreline, the average velocity of the water, the average direction of flow of the water in relation to the shoreline, the depth of the water, the density of the sediment material to be transported.
There have been many devices and methods of hydraulic and earth engineering employed to preserve shorelines or other areas subject to the erosive influence of moving water. The main existing method of combating erosion is to simply renourish an eroding beach with a fresh supply of dredged sand. However, this existing method has many problems. The dredged sand often does not match the existing color of sand on the beach and diminishes the aesthetic appearance of the beach. The dredged sand can also contain rocks or other solid objects that can hinder water sports, such as swimming or surfing, and can injure or hurt the bare feet of beachgoers upon walking on a renourished beach.
Other methods of preventing shoreline erosion include installation of structures near the shoreline. One example includes laying down a plurality of block members end-to-end from each other along the shore line and, further, another plurality of block members on top of the original layer of block members to provide a wall over which the wave action can pass. The wall constructed by this plurality of block members requires connecting components, such as locking pins, to secure the plurality of blocks together. However, the construction of the shore erosion control wall is labor intensive and time consuming.
Still other methods of preventing shoreline erosion is to fortify the eroding shoreline with blocks, cement, and the like, to form a prophylactic layer over the region of the shoreline that would otherwise be subject to the erosive effects of waves. However, due to the weight and bulk of the fortifying materials, such “armoring” techniques are often difficult to install on the shoreline and problematic to adequately anchor the armor to the underlying shoreline, whether beach, bank, or both. The armored structures often result in permanent structures that are not easily removed from the shoreline and prevent full enjoyment of the region of the shoreline that they overlay.
These structures are typically constructed in shallower waters, for example in depths lying under eighty feet, and simply comprise piled masses of stone or rubble laid on the sea floor to dissipate or attenuate wave energy. In order to attenuate a sufficient amount of wave energy, the structure may be required to be built twenty to thirty feet higher than mean sea level with a base often spanning two hundred feet or more. In many harbor locations, the great mass and size of stone suitable for construction of either vertical wall breakwaters or of capped rubble mounds is not available locally. The wave resisting upper layers of rubble mounds are required to be made of boulders, each weighing many tons, so that the construction of these massive piles of rock involves heavy capital expenditure where the stone must be hauled from remote quarries.
Furthermore, in marsh settings, where weak organic soil is present, the seabed may not adequately support structures that are positioned thereon, such as rocks or blocks. Therefore, unless a shoreline protection system is supported by bases, piles, or a foundation that is deeply imbedded beneath the surface of the seabed, the structure will progressively sink.
Other shore and bank protection techniques and devices known in the art attempt to control erosion by attenuating the energy, velocity, and/or direction of potentially erosive waves and subsurface water currents with the use of certain temporary structures placed on the shoreline. Some of these devices are porous groin structures, which use either flexible or rigid nets, screens, or filters placed in close proximity to the shoreline, substantially perpendicularly to the shoreline, and extending into the surf. The porous groins are placed in the tidal and longshore currents and function much in the same way as a jetty, causing sand to accrete around the porous groin. The porous groin must be constantly moved or removed from the accreting sand or else it becomes stuck in the sediment, requiring extreme forces to be used to dislodge the porous groin from the accreted sediment.
Accordingly, a need exists for a device and method of shoreline protection and/or restoration having a simple construction and disassembly, and whose mass is relatively small in comparison with conventional sea walls or rubble mounds.
Furthermore, a need exists for a device and method for shoreline protection and/or restoration that uses temporary structures to protect and repair the beach by effectively attenuating water wave energy.
A need exists for a shoreline protection system that will not sink when used in marsh settings where loose soil or weak organic soils are present.
Lastly, a need exists for a shoreline protection system that reduces, eliminates, or reverses shoreline erosion while minimizing adverse environmental impacts to the surrounding marsh, with minimal disruption of tidal circulation, fish and marine organism passage, and sediment transport. Such systems and methods should allow the shoreline to undergo natural accretion of sand and sediment while reclaiming the beach without adversely altering the surrounding shoreline.
Embodiments usable within the scope of the present disclosure meet these needs.